Conversion of analog images into digital data has become widespread for a variety of applications, including storing, manipulating, transmitting and displaying or printing copies of the images. For example, images captured in photographic media are converted to digital data and stored on compact discs for readout and display as a video image, as exemplified by the KODAK.RTM. Photo-CD system, or reproduced employing various types of color printers. In order to convert the photographic image into a set of digital line data, the film image frame is transported through a film scanning station past, and illuminated in each scan line with a linear light beam of uniform, diffuse illumination, typically produced by a light integrating cavity or integrator.
The light transmitted through the illuminated scan line of the image frame is focused by a lens system on a linear CCD array, image detector which typically produces three primary color light intensity signals for each image pixel that are digitized and stored. The digitized signal values for each scan line may be formatted to a standard for video recording and display and stored on compact disc or magnetic media. Such film scanners take a variety of forms, and the various common aspects of film image frame digitizing, particularly line illumination and linear CCD array-based digitizers, are described in greater detail in commonly assigned U.S. Pat. No. 5,155,596.
In order to perform line scanning of an image frame of photographic negative filmstrips, it is necessary to provide an accurate film transport mechanism to transport a filmstrip into a scanning gate and hold the image frame flat in alignment with a scanning aperture. In one scanner type, the linear CCD array and scanning light beam are stationary so that the light beam illuminates a line of the filmstrip image frame, and a line of digitized data is stored. The film scanning gate and clamped slide or filmstrip image frame is incrementally moved or translated line-by-line until the entire image frame is digitized. Then a new image frame is positioned and flattened for scanning and digitizing. Such a scanning and digitizing system for Photo-CD conversion is embodied in the KODAK.RTM. PIW Model 2400 Photo-CD scanner system marketed by the assignee of this application.
In this film scanner, the scanning plane is vertical and the stationary scanner components are oriented horizontally. An operator introduces the negative filmstrip from the left side into a slot leading to a film track and drive mechanism to position an image frame in a filmstrip scanning gate and the image frame is clamped. A belt driven roller assembly advances the film strip through the filmstrip scanning gate past the stationary scanner components in a first pass for scanning the clamped image frame at a low resolution sufficient to provide a video display of the image frame on a monitor for viewing by the operator.
The color balance of the scanned and digitized image pixel data is automatically adjusted to the color balance characteristics of the video display. The operator may further adjust the displayed color balance or tone and intensity of the color display while viewing the result of the adjustments until satisfied, whereupon the adjustment factors for that image frame are stored. The orientation of the image may also be stored with the digitized data so that the CD player can rotate the image data 90.degree. for display as a video image at the same aspect that the image was captured by the photographer.
As each image frame is scanned in this first pass, the scanned image frames of the vertically oriented filmstrip are advanced into a stationary take-up chamber. The take-up chamber is provided within the scanner to temporarily hold the filmstrip and isolate it from other apparatus that it could catch on and to keep it clean.
After all image frames are scanned, the trailing end of the filmstrip is advanced in the reverse direction into the filmstrip scanning gate one frame at a time. The filmstrip image frame is clamped and a focus adjustment is made by a scanning lens auto-focus system. After auto-focus, a translation stage translates the image frame to the start scan position, and then translates each image frame through the scanning station. The image frame is scanned at high resolution for digitizing the image as a field of data associated to the data derived in the low resolution scan of the same image frame. As the next image frame is advanced into the scanning gate, the filmstrip is transported back out the same slot that it was slipped into for removal by the operator when scanning of all frames is completed. Thus, positioning of the next filmstrip to be scanned must await the complete ejection of the filmstrip being scanned.
The filmstrip scanning gate includes the filmstrip scanning aperture, a clamp for flattening the image frame, the filmstrip drive roller assembly and a sensor for deriving perforation signals for use in re-positioning the image frames for high resolution scanning. It is possible to scan positive color transparencies in mounts, i.e. slides, in the Model 2400 Photo-CD scanner employing common components of the same film scanner station. To do so, it is necessary for the operator to manually replace the filmstrip scanning gate and substitute a slide clamp and scanning gate, in its place on the translation stage. The slides are manually inserted into a clamp so that one side of the slide mount is fitted against a fixed aperture frame. Thus, the slide scanning plane varies with the thickness of the slide mount, requiring re-focus of the scanning lens to the image plane.
The scanning area is left open in this film scanner to allow frequent replacement of the scanning gates, and the scanning station is therefore open to the infiltration of dust particles. The exchange of the scanning gates is tedious and mechanical breakdowns are possible in attempting the exchange. Moreover, the scanning gates are subject to damage when they are carelessly handled or stored when not in use. Finally, the process is slow and productivity in scanning slides is low.
A lower resolution scanning and digitizing system of either a negative filmstrip or a positive slide for direct display as a video image is generally disclosed in commonly assigned U.S. Pat. No. 4,858,003. The '003 patent describes a mechanism for introducing and ejecting individual slides from a slide receiver frame forming a slide scanning gate defining a nominal slide scanning plane for the slide film. The slides are held flat with one mount side against the frame surrounding the scanning aperture. The actual slide film position may therefore be spaced from the nominal slide scanning plane by a distance depending on the thickness of the slide mount.
Negative filmstrips are fitted into an elongated carrier similar to a slide mount. Individual image frames are introduced into and aligned with a separate filmstrip scanning plane spaced from the slide scanning plane.
The optical system is adjusted to the slide and filmstrip scanning planes when either slides and negative filmstrip carriers, respectively, are presented for scanning. Such a gross adjustment each time a slide or filmstrip is to be scanned is time consuming.
In a further Kodak.RTM. RFS 2035 scanner, an auto feed slide device made by MARON, INC. feeds slides from a spring-loaded, horizontal hopper into a slide track. The parade of vertically standing slides move horizontally along their edge and are pushed out of the hopper and through a hopper slot with a shuttle device. The shuttle cannot feed slides from the hopper to the slide gate unless all the slides in the hopper are the same thickness and can pass through the hopper slot. The hopper slot can be manually adjusted for various slide thicknesses, but does not automatically do so. The slides are pushed toward the CCD area array so that one side of the slide mount is forced against a frame.
Problems to be Solved by the Invention
It is desirable to improve the speed and operating efficiency of film scanners by obviating the need to manually replace the slide and negative filmstrip scanning gates and associated mechanism to alternately scan slides and negative filmstrips. To satisfy this desire, there is a need for a filmstrip and slide handling apparatus that accepts either in the respective scanning gate and automatically positions it in the scanning station, completes the scanning and ejects the slide or filmstrip.
There is also a need for such a film scanner having a negative filmstrip scanning gate that clamps the negative filmstrip image frame in a film scanning plane and slide scanning gate for automatically registering its image frame in the film scanning plane regardless of variations in the thickness and side dimensions of various slide mounts to decrease the need for focusing the imaging lens of the film scanner.
Furthermore, there is a need for a film scanner that accepts more than one negative filmstrip for scanning so that productivity may be increased.